Description: (provided by the applicant) The long-term goal of this project is to develop a non-invasive, noise-based technique for improving tactile sensation in elderly individuals and patients with sensory deficits, thereby improving posture control. In previous studies, we have shown that input noise (mechanical or electrical) can significantly enhance the ability of healthy young subjects to detect subthreshold mechanical cutaneous stimuli. Recently, in a pilot study, we also showed that vibrotactile detection-thresholds in older adults, patients with stroke, and patients with diabetic neuropathy can be significantly reduced with the introduction of mechanical noise. In this project, we plan to build upon this work and explore the functional benefit of noise-enhanced vibrotactile sensory function, particularly its effect on biomechanical measures of postural stability. The specific aims for this project are: (1) to determine the effects of input mechanical noise on vibrotactile detection thresholds at the feet; (2) to determine the effects of noise-enhanced somatosensation at the feet on an individual's ability to maintain balance; and (3) to determine the effects of adaptation on noise-enhanced balance control. To accomplish these aims, we will conduct a series of psychophysical tests and quiet-standing posture tests on healthy young individuals, older adults, patients with stroke, and patients with diabetic neuropathy. In the psychophysical tests, each subject's detection thresholds for a vibrotactile stimulus, with and without mechanical noise, will be determined. The posture tests will be conducted with a motion analysis system, and sway parameters previously shown to be associated with falls will be computed and correlated with vibrotactile detection threshold changes. These studies will take advantage of the OAIC Recruitment Core and the Evaluation and Biostatistics Core. This project could lead to the development of a novel bioengineering technique for improving human balance control. The proposed work could thus serve to reduce significantly the frequency, morbidity and cost of falling and assist aged individuals in achieving maximum independence in activities of daily living and mobility.